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MOST BRANDS THAT USE R22 SAY .6 OUNCES OF R22 PER FOOT OF LINESET OVER THE RATED LENGTH [WHICH IS EITHER 15 OR 25 FEET DEPENDING ON THE BRAND.] BUT YOU STILL HAVE TO CHECK SUPERHEAT OR SUBCOOLING DEPENDING ON THE METERING DEVICE.

Originally posted by r22dave MOST BRANDS THAT USE R22 SAY .6 OUNCES OF R22 PER FOOT OF LINESET OVER THE RATED LENGTH [WHICH IS EITHER 15 OR 25 FEET DEPENDING ON THE BRAND.] BUT YOU STILL HAVE TO CHECK SUPERHEAT OR SUBCOOLING DEPENDING ON THE METERING DEVICE.

Good question JRC. And for the most part the answer has been posted. For 3/8" you would add .6 oz per foot beyond the nameplate charge for the distance beyond whats rated as mentioned 15 or 25 feet, and any drier installed (a c163 sporlan holds like 13 oz if I remember correctly).

Most if not all mfg's have restrictions on how long and how much vertical speration can be added. For instance, if you are working a Carrier unit, there is a long line guide you need to consult which suggests a cc heater, liquid line solenoid valve and even wind baffles in some cases. That long line guide is for carrier equipment not trane, york, rheem or anyone elses. They each have guidelines to follow.

I tell you this much, many units are installed with linesets lengths that are just not supported. Definately consult your installation instructions carefully to make sure you are within the operating limits.

For instance a 3 ton with a match that actually provides 34,500 btuh's total with a correction factor of .95 The sensible capacity is also affected lets say this unit has a sensible capacity of 25,600.

34,500*.95=32,775 total capcity
25,600*.95=24,320 sensible capacity

The unit has now a total capcity of 32,775 and a sensible capacity with a re-rate to 24,320.

The information is provided so you can best select the equipment based on the load calculations. In other words if for instance this home required a 28,000 sensible capcity unit, this unit would be undersized.